1. Field
The present invention generally relates to a memory system, a memory control method, and a recording medium storing a memory control program.
2. Background
The recent image processing apparatuses such as printers, copiers, scanners, and multifunctional peripherals, and information processing apparatuses such as computers are provided with nonvolatile memories having high processing speeds and large capacity sizes such as dynamic random access memories (DRAMs) including, for example, double data rate (DDR)3-SDRAM. SDRAM is integrated as a dual inline memory module (DIMM), which is made in compliance with Joint Electron Device Engineering Council (JEDEC) standards.
For example, the JEDEC committee standardizes a small outline dual in-line memory module (SO-DIMM) used for DDR3 SDRAM in the form of a specification called a Rawcard, which includes: Rawcard-A (2Rank x16 SDRAM), Rawcard-B (1Rank x8 SDRAM), Rawcard-C (1Rank x16 SDRAM), Rawcard-D (2Rank x8 stacked SDRAM), and Rawcard-F (2Rank x8 SDRAM). These Rawcards are all designed for a 64-bit DIMM.
Since the DDR3 SDRAM that is available in the market has a chip capacity of 1 GB (gigabytes) or 2 GB, the capacity sizes of a DIMM are 1 GB or 2 GB for Rawcard-A on which 8 devices are mounted, 512 MB (megabytes) or 1 GB for Rawcard-B on which 8 devices are mounted, 512 MB or 1 GB for Rawcard-C on which 4 devices are mounted, 1 GB or 2 GB for Rawcard-D on which 8 devices are mounted, and 1 GB or 2 GB for Rawcard-F on which 16 devices are mounted, respectively. Accordingly, a DIMM for SO-DIMM has a capacity size of 512 MB, 1 GB, or 2 GB for 8 devices, and 512 MB or 1 GB for 4 devices, as specified by Rawcards. This indicates that, for a system that requires a capacity ranging between 1 GB and 2 GB with a 64-bit bus width, 8 devices are typically used. For a system that only requires a low capacity of 512 MB or less, at least 4 devices are used. Thus, it has been difficult to design a memory system having a low capacity with reduced costs using the DDR3 SDRAMs that are available in the market.